He imposed a six-week jail sentence, suspended for 12 months, and also imposed a 10-year ban on him keeping animals.

First of all, this chap should have been banned from ever owning a pet again, not 10 years but for life. No animal would ever be safe in his possession ever again.
If he felt the need to dispose of the dog then most likely due to its symptoms it would have been put down ethically by a vet anyway, this is psychopathic behaviour and I wonder how on Earth any human would escape prison committing such a crime. This is not the only case of this as a dog was found to have been drowned by a mud weight around the Thurne area, or was Potter Heigham, I cant be sure now.
I find it distressing enough seeing swans wrapped up in fishing line but to hear of people drowning dogs makes my blood boil.